1. Field of the Invention
The present invention relates to a substrate for growing a single crystal diamond layer to produce a single crystal diamond substrate, and a method for producing a single crystal diamond substrate.
2. Description of the Related Art
Diamond has a wide band gap of 5.47 eV and a very high dielectric breakdown electric field intensity of 10 MV/cm. Furthermore, it has the highest thermal conductivity in materials. Therefore, if this is used for an electronic device, the device is advantageous as a high output power device. Furthermore, diamond has a high drift mobility and is the most advantageous as a high speed power device in semiconductors in comparison of Johnson performance index.
Accordingly, diamond is said to be the ultimate semiconductor suitable for high frequency/high power electronic devices. Therefore, studies of various kinds of electronic devices using a single crystal diamond for a substrate has progressed.
Now, the single crystal diamond substrate for producing a diamond semiconductor is diamond referred to as Ib type, which is formed by a high-pressure-high-temperature method (HPHT), or diamond referred to as IIa type, of which purity is enhanced.
However, it is difficult to grow in size while the HPHT method can provide the diamond having high crystallinity. Therefore, a price of the diamond becomes extremely high when its size becomes big and consequently, it is difficult to put into practical use as a substrate for the devices.
Accordingly, a CVD single crystal diamond formed by a vapor deposition method is also studied to provide a low cost substrate having a large area.